Preparation And Application Of Room Temperature Crosslinked Polyphospazenes

Polyphosphazenes are a class of organic-inorganic hybrid polymer compounds whose main chain is composed of phosphorus and nitrogen atoms arranged in an alternating structure of single bonds and double bonds,and whose side chains are composed of organic or inorganic groups.The main chain structure of polyphosphazene contains only phosphorus and nitrogen elements with flame retardant properties,which makes it have flame retardant and high temperature resistant properties compared with conventional carbon chain materials,while the good flexibility of the main chain endows the material with excellent low temperature resistance.The properties of polyphosphazene polymers are greatly affected by the two side groups on their phosphorus atoms.Connecting different side groups can endow polyphosphazene materials with many excellent physical and chemical properties.Therefore,it is a research hotspot to explore the introduction of different groups into the side chains to prepare functional polymer materials with different properties.Coating materials are easy to be polluted by water and oil stains,thus affecting their appearance and performance.Coating research with amphiphobic properties(i.e.hydrophobic and oleophobic)can be widely applied in the fields of buildings,transportation,public facilities and the like.Fluoroalkoxy polyphosphazenes not only have hydrophobic and oil-resistant properties,but also have a series of excellent properties such as flame retardancy,easy film formation,low temperature resistance and aging resistance.When they are used to prepare amphiphobic coatings,their comprehensive properties can be expected to surpass those of conventional fluorocarbon polymers or coatings without fluoropolymer base.However,it has been reported that fluorinated alkoxy polyphosphazenes are difficult to achieve effective curing crosslinking at near room temperature(e.g.,below 60 C°).Therefore,it is a challenging research topic to carry out the synthesis and preparation of fluorine-containing polyphosphazenes that can be crosslinked near room temperature.This paper attempts to introduce quantitative high-activity groups(such as amino,hydroxyl and other functional groups)into the side chain of linear polyphosphazene,so that it can react with isocyanate materials through the active hydrogen of the introduced active functional groups to realize rapid curing and crosslinking at room temperature,so as to improve the problems of slow curing and complicated process conditions in the construction and molding of such materials.In the experiment,the target functional group was introduced through nucleophilic substitution reaction of poly dichlorophosphazene.The technical scheme of active group protection and deprotection is specifically adopted.Polyphosphazene derivatives with different functional group contents were obtained by adjusting the input ratio of nucleophiles.The structures and properties of the products were characterized by nuclear magnetic resonance spectrometer,thermogravimetric analyzer,differential scanning calorimeter and other instruments and equipment.The water contact angle of the fluorine-containing amphiphobic coating prepared in the experiment can be adjusted from 76° to 115° according to the difference of amino content in the material.After 500 hours of ultraviolet aging experiment,the hydrophobicity and oil resistance of the material do not obviously decrease,and the coating also has good resistance to acid and alkali and salt solutions.Observation by scanning electron microscope and atomic force microscope shows that the material has uniform structure and no obvious defects,suggesting that it is expected to have potential application value as an excellent amphiphobic coating material.